1. Field of the Invention
The invention concerns a press-driven tool module, in particular a press-driven cross-punching or bending unit comprising a work ram slidably mounted in a cylindrical bore and adapted for receiving a work tool, a hydraulic power cylinder, a vertically displaceable plunger mounted in said hydraulic power cylinder, and a press ram disposed for acting upon said plunger, and a hydraulic pressure line communicating between the power cylinder and the work cylinder, such that the press ram acting on the plunger causes transmission of pressure through the hydraulic lines to said work cylinder.
2. Description of the Related Art
This type of work tool module is known for example from the brochure "MILFAB" of Danly Deutchsland GmbH. It is comprised of a ram or pushrod onto which a work tool, in particular a cross-punching or bending tool, is provided. The ram is mounted slidably in a guide box within a foundation. The direction of sliding is determined by the orientation of the guide box and runs horizontally. Parallel to the ram, either within or outside of the foundation, a coil spring is provided connected with the ram in such a manner that it opposes the sliding action of the ram and serves as a return spring. The end the ram opposite the work tool end is acted upon by a rocker arm. This is mounted pivotally in the foundation and is vertically acted upon by a press ram. As a result of the downward movement of the press ram during the operating stroke, the rocker arm pivots about its axis and thereby pushes the work tool carrying ram in the forwards direction. After the cross-punch or bending process there follows the return stroke of the press ram as well as the return movement of the work tool carrying ram as a result of the operation of the return spring. The return spring is necessary for the reason that the press ram is not rigidly connected with the tilt lever. More particularly, the press ram has, when at top dead center, no contact with the rocker arm.
This type of work tool module has found wide acceptance since it is universally capable of being incorporated in all conventional presses. It is mounted therein in the desired position. For this, various means of securing such as, for example, bore holes, adjusting spring slots or recesses, are provided in the foundation.
Nevertheless, they exhibit a series of disadvantages. It is necessary that the rocker arm acting as a force redirecting organ is subject to very strong wear forces, since the transference of high forces must occur at the pivot axis. The same can be said for the sliding surfaces of the rocker arm lever which are in contact with the press ram and with the tool carrying ram. Further, this type of work tool module has little flexibility with respect to possibilities of multi-unit arrangements. In the case that it is desired to provide a multi-unit arrangement, there is little flexibility since as a rule only one rocker arm can be operated respectively by a press ram. For this reason an expensive and complicated construction is frequently necessity in order to permit multiple work tools to be operated at the same time using one main rocker arm. Once a particular geometric construction has been selected it must as a rule be maintained; even minimal modifications in the geometry result in the need for special customized construction of a new work tool module.